1. Field of the Invention
The present invention relates to a ceramic substrate employed in an apparatus for inspecting electronic components, for instance, a probe card, and a method for manufacturing the ceramic substrate.
2. Description of Related Art
A multilayer ceramic substrate made of a plurality of ceramic layers has hitherto been used as a substrate for a probe card that is one of the pieces of an electronic component inspection apparatus.
A plurality of vias (filled with a conductive material) and internal wiring layers connected to the vias are provided in the ceramic substrate. A plurality of pads connected to the respective vias is formed on a surface of the ceramic substrate (see Patent Document 1).
In the probe card, microscopical probes are connected onto pads on a ceramic substrate. The probes are brought into contact with the electrodes of a plurality of semiconductor chips (e.g., IC chips) fabricated on, for instance, a silicon wafer, to electrically inspect the semiconductor chips.
When the ceramic substrate is manufactured, a plurality of ceramic green sheets (corresponding to ceramic layers) having (unsintered) vias and internal wiring layers are usually manufactured. The ceramic green sheets are stacked, to thus fabricate a layered product. The layered product is sintered and subsequently separated, thereby forming ceramic substrates having predetermined shapes.